__vm_create_guest_memfd
fd = __vm_create_guest_memfd(vm, size, guest_memfd_flags);
fd1 = __vm_create_guest_memfd(vm, page_size, 0);
fd2 = __vm_create_guest_memfd(vm, page_size * 2, 0);
fd = __vm_create_guest_memfd(vm, page_size, flag);
int fd = __vm_create_guest_memfd(vm, size, flags);